Method for treating plastic film and a device in a wrapping machine

ABSTRACT

A method and device for treating plastic film, according to which method plastic film web used as packaging material is wrapped around the object to be packaged. According to the method, the plastic film layers are seamed together and the plastic film web is cut off by heating the seaming point and cutting-off point by means of a heat radiator. Heat-absorbent counterpieces are preferably placed at both the seaming point and the cutting-off point, the said counterpieces being heated through the plastic layers. When the counterpieces absorb heat from the heating radiator, they heat up and at the same time heat the plastic films to be seamed and cut off. In the most advantageous embodiment, the infrared heat radiator is placed inside a tubular gripping counterpiece, which gripping counterpiece comprises slots through which the heat radiation is able to pass to the counterpieces. The color and degree of darkness of the counterpieces has been selected such that they bring about the desired temperatures in the plastic films.

FIELD OF THE INVENTION

The object of the invention is a method for treating plastic film inpackaging by wrapping, according to which method plastic film web usedas packaging material is wrapped around the object to be packaged, thesaid web being treated thermally to seam the plastic films and/or to cutoff the plastic film web. In the packaging sector, a widely usedpackaging method is one where the object to be packaged is wrappedinside a thin plastic film. The plastic film used in such a case isusually plastic film web which is unwound from a roll and wrapped aroundthe object to be packaged.

The object of the invention also includes a device in a plastic filmwrapping machine, which comprises wrapping means for wrapping theplastic film around the object to be packaged, and treatment means forthermally treating the plastic film, the said treatment means comprisinga seaming device for seaming the plastic films and/or a cutting devicefor cutting off the plastic film web. Thus the method and device areapplicable to a wide range of packaging machines. There are manual,semi-automatic and fully automatic wrapping machines.

DESCRIPTION OF THE PRIOR ART

Manual wrapping machines are usually turntable machines in which onlythe object to be packaged is rotated by means of a motor. Otherfunctions, such as moving the object, start of wrapping, lifting andlowering the plastic film roll carriage, seaming, cutting and finishingof wrapping are all carried out manually. There are also manual rotaryarm wrapping machines, in which the plastic film roll is rotated aroundthe object to be packaged by means of an arm.

Semi-automatic packaging machines are usually also turntable machines orrotary arm wrapping machines. In these machines, the object to bepackaged has to be moved to the wrapping station and away from itseparately. These machines also lack automatic plastic film seaming orautomatic plastic film web cutting.

In a fully automatic packaging machine, the object to be packaged ismoved and the package handled automatically. The pallet on which theobject to be packaged Is placed is fed into the wrapping machine bymeans of a conveyor, the object is wrapped in plastic film, the plasticfilm is seamed, the plastic film is cut off and the packaged object isconveyed away from the wrapping machine. All this takes placeautomatically. The handling of the next object to be packaged alsostarts automatically, in the same manner. With a fully automaticpackaging machine, human intervention is usually only needed when theroll of plastic packaging film runs out. Someone is then needed tochange the empty roll for a full one. Fully automatic plastic filmwrapping machines are usually ring wrapping machines, turntable machinesor rotary arm wrapping machines. Ring wrapping machines are generallyalways fully automatic.

The method and device relating to the invention can be applied to any ofthe above mentioned packaging machine types. The greatest advantagesare, however, achieved with a fully automatic packaging machine, theefficiency of its operation increasing substantially as a result of themethod and device relating to the invention. This is why the inventionis described in the following, by way of an example, when connected toan automatic ring wrapping machine. It is, however, obvious that thisonly serves as an example, which does not restrict the use of theinvention in other packaging machines.

A known plastic film packaging machine is the type of ring wrappingmachine in which a roll containing plastic packaging film is placed in awrapping carriage positioned in a circular rotation ring. The object tobe packaged is placed in the centre of the circular rotation ring.Packaging takes place so that the rotation ring with its wrappingcarriage rotates around the object to be wrapped, thus unwinding theplastic packaging film from the roll and winding it around the object tobe packaged. Alternatively, the object to be packaged may rotate and theplastic film web be unwound from a plastic film roll moving vertically,which is the case with turntable wrapping machines.

On a known ring wrapping machine, when packaging is started, the end ofthe plastic film web unwinding from the roll is fastened to the grip ofthe gripping unit incorporated in the packaging machine. By means of thegripping means, the leading end of the plastic film web is held in placewhen wrapping is started. In this machine, the gripping means ispositioned on the frame of the packaging machine in such a way that itwill not rotate with the rotation ring. When at least one round ofwrapping film web has been wrapped around the object to be packaged, theend of the plastic film web is detached from the hold of the grip. Thedetached end of the plastic film web then falls on top of the alreadywound layer of plastic film web and remains under the next plastic filmlayers which are wound over it. Since the surface of the plastic filmweb is sufficiently tacky, the layers of the package which are on top ofeach other will not slide but remain firmly in place.

In a ring wrapping machine, packaging is stopped when a sufficientamount of plastic film web has been wound around the object to bepackaged, by seaming the plastic film web and cutting its end off. Whenseaming takes place, at least the two topmost web layers are seamedtogether and the web is cut adjacent to the seam. Seaming is usuallydone so that once the actual wrapping has been completed, the seamingcounterpiece of the seaming device is placed above the plastic films ofthe package, at a distance from the topmost plastic film. After this,another one or two layers of plastic film are wrapped around thepackage, thus leaving the seaming counterpiece under these layers. Theactual seaming takes place by bringing several band-like thermalresistors heated to a suitable temperature to the position of theseaming counterpiece, and pressing the said resistors momentarilyagainst the seaming counterpiece. As a result, the seaming layers of theplastic film web are pressed between the seaming counterpiece and thethermal resistors, which causes the plastic films of the seaming layersto melt and adhere to each other at the points where the thermalresistors are located.

In a known ring wrapping machine, the thermal resistor bands used inseaming are usually parallel with the plastic film web, thus formingseveral adjacent seams having the same length as the resistor bands. Thethermal resistor bands are parallel with the plastic film web becausecross-web thermal resistors might melt and cut the plastic film web whenseaming takes place. When the thermal resistor is moved away from thevicinity of the seam, the seam cools rapidly and the seamingcounterpiece can be pulled away from between the packaging plasticlayers.

Before the plastic film web is cut off, the gripping means of thegripping unit incorporated in the machine grips the plastic film web inthe vicinity of the cutting-off point so that the end unwinding from theroll, which remains free, can be taken close to the next object to bepackaged in order to start its packaging. The plastic film web is cutoff adjacent to the seam by bringing a thermal resistor wire close tothe plastic film web running from the package to the roll. When thethermal resistor wire is heated, the plastic web also heats up to suchan extent that it is cut off by melting. After this, the wrappingplastic film package is complete.

Once the packaged object has been removed from the packaging machine anda new object has been brought in its place, the packaging of the nextobject is started by bringing the end of the plastic film web, by meansof the grip, close to the object to be packaged and proceeding with thewrapping as described above.

SUMMARY OF THE INVENTION

The aim of the present invention is to increase the efficiency ofoperation of the plastic film packaging machine disclosed above and toachieve a new method and device for finishing off the plastic packagingfilm once the desired number of plastic film web layers have beenwrapped around the object to be packaged.

It is characteristic of the method relating to the invention that inpackaging by wrapping, plastic film is treated, so that one or moreplastic film webs are heated by means of at least one heat radiator inorder to seam the plastic film webs together and/or to cut off theplastic film web.

According to an advantageous embodiment, two or more plastic film websare seamed together in such a way

that a heat-absorbent counterpiece is placed under the plastic filmlayers at the seaming point, the said counterpiece being heated by meansof an infrared heat radiator through the plastic film layers, and

that the counterpiece is allowed to absorb the heat from the infraredheat radiator so that it heats up and at the same time heats the plasticfilm layers to be seamed in such a way that the plastic film layers areseamed together.

According to another advantageous embodiment, the plastic film web (22)is cut off in such a way

that a heat-absorbent counterpiece is placed behind the plastic film webat the cutting-off point, the said counterpiece being heated by means ofan infrared heat radiator through the plastic film web, and

that the counterpiece is allowed to absorb the heat from the infraredheat radiator so that it heats up and at the same time heats the plasticfilm web to be cut off so that the plastic film web is cut off.

It is characteristic of the device relating to the invention that theplastic film wrapping machine comprises at least one heat radiator bymeans of which one or more plastic film webs can be heated in order toseam them together and/or the plastic film wrapping machine comprises atleast one heat radiator by means of which the plastic film web can beheated in order to cut it off.

According to an advantageous embodiment of the device relating to theinvention, the seaming device comprises an infrared heat radiator and atleast one heat-absorbent counterpiece, and means for placing theinfrared heat radiator and the heat-absorbent counterpiece on oppositesides of the plastic film layers to be seamed.

According to another advantageous embodiment of the device, the cuttingdevice comprises an infrared heat radiator and at least oneheat-absorbent counterpiece, and means for placing the infrared heatradiator and the heat-absorbent counterpiece on opposite sides of theplastic film layers to be cut off.

The invention enables both more rapid seaming and cutting and at thesame time improved reliability and appearance of the seam. According toyet another advantageous embodiment, the infrared heat radiator isplaced inside a tubular gripping counterpiece, the said grippingcounterpiece having slots or apertures through which the heat radiationis able to pass to the counterpieces.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in the following by means of an example, withreference to the appended drawings in which

FIG. 1 shows a diagrammatic side view of the plastic film wrappingmachine and the object to be packaged at the start of packaging.

FIG. 2 corresponds to FIG. 1 and shows the second stage of packaging.

FIG. 3 corresponds to FIG. 1 and shows the start of package seaming FIG.corresponds to FIG. 3 and shows the second stage of package seaming.

FIG. 5 corresponds to FIG. 3 and shows the third stage of packageseaming.

FIG. 6 corresponds to FIG. 3 and shows the fourth stage of packageseaming.

FIG. 7 shows a diagrammatic view of the plastic film wrapping machine ofFIG. 1 and the object to be packaged in the situation shown in FIG. 6,as seen from above.

FIG. 8 corresponds to FIG. 3 and shows the fifth stage of packageseaming.

FIG. 9 corresponds to FIG. 7 in the situation shown in FIG. 8.

FIG. 10 corresponds to FIG. 7 and shows the sixth stage of packageseaming.

FIG. 11 shows a detail of FIG. 10.

FIG. 12 corresponds to FIG. 1 at the finishing off stage of packaging.

FIG. 13 corresponds to FIG. 11 and shows a second embodiment of theplastic film wrapping machine.

FIG. 14 shows a detail of FIG. 13.

FIG. 15 shows the gripping arm of the plastic film wrapping machine, asseen from the side.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 shows diagrammatically the object 20 to be packaged placed onbase 21, and the film roll 23 containing the plastic film web 22 usedfor packaging. The film roll 23 is placed in a wrapping carriage whichmoves on a circular rotation ring. The carriage is not shown. Of theactual packaging machine, the figure only shows the gripping unit 30,between the gripping counterpiece 31 and gripping arm 32 of which isfastened the end 24 of the plastic film web 22. FIG. 1 also shows theseaming counterpiece 33 situated on the gripping unit.

The wrapping of a package is started by manually fastening the end 24 ofthe plastic film web 22 unwinding from the film roll 23 between thegripping counterpiece 31 and the gripping arm 32 of the gripping unit30. This has to be done every time the film roll 23 runs out or isreplaced for some other reason. At the other stages, the plastic film 22does not need to be touched by hand, because when the film is cut, thegripping counterpiece 31 and gripping arm 32 of the gripping unit 30always grip that end of the film web 22 to be cut which remains on theside of the film roll 23, as seen from the cutting-off point. Thisenables automatic package wrapping even if the object to bet packaged 20is changed. This can be continued until the film roll 23 runs out and isthen replaced with a new full one. When wrapping starts, the grippingcounterpiece 31 and gripping arm 32 of the gripping unit 30, and theseaming counterpiece 33, are in their uppermost position and the end 24of the plastic film 22 is between the gripping counterpiece 31 and thegripping arm 32. The film roll 23 is placed in a wrapping carriage whichmoves on a circular rotation ring, from which carriage the film 22unwinds automatically. The rotation ring and wrapping carriage are notshown in FIG. 1.

FIG. 2 shows the second stage of packaging by wrapping in which the end24 of the plastic film 22 is detached from the gripping unit 30 afterthe first full wrapping round. The gripping unit 30 is opened by turningand opening the gripping arm 32. The detaching movement of the grippingarm 32 is about 90°, during which the gripping arm 32 moves to the lowerposition and returns back up. The purpose of the movement is to ensurethat the plastic film is actually detached from the gripping unit 30. Asa result of being detached, the end 24 of the plastic film 22 falls downon top of the first layer of wrapping 25. When the next round of plasticfilm is then wound, the end 24 of the film 22 remains under the secondfilm layer. Thus the end 24 of the film 22 is fastened tightly betweenthe first and second film layers.

After the first rounds, wrapping is continued by wrapping the desirednumber of packaging film layers around the object to be packaged. On topof these layers are then added so-called seaming rounds, the purpose ofwhich is to achieve a sufficiently thick seaming layer to obtainreliable seaming.

FIG. 3 shows the start of package seaming, where, immediately followingthe last package wrapping round 26, the seaming counterpiece 33 islowered down on top of the packaging film layers, at a distance from thetopmost plastic packaging film. As a result, the next layer, that is,the first plastic film 22 seaming layer 27 is wound over the seamingcounterpiece 33, as shown in FIG. 4.

Immediately after the first seaming round 27 of the plastic film 22, thegripping arm 32 and the gripping counterpiece 31 are lowered downtogether. The gripping arm 32 is, however, turned back up again, butthis time to the opposite side. This situation is shown in FIG. 5.

In the next wrapping round, that is, the second seaming round, theplastic film 22 passes under the gripping arm 32 and the second seaminglayer 28 is wrapped over the gripping counterpiece 31. The situation isshown in FIG. 6 as seen from the side, and in FIG. 7 as seen from above.

When the plastic film 22 comes into contact with the grippingcounterpiece 31 during the second seaming round, the wrapping carriageis stopped and the plastic film 22 feed is discontinued. After this, thegripping arm 32 is turned back down again, towards the grippingcounterpiece 31, so that the plastic film 22 remains pinched between thegripping arm 32 and the gripping counterpiece 31, as shown from the sidein FIG. 8, and from above in FIG. 9.

For the purpose of seaming, the seaming counterpiece 33 or a separateseaming surface belonging to it, is pressed against the gripping arm 32,as shown in FIG. 10. As a result, the two topmost plastic film layersare pressed between the seaming counterpiece 33 and the gripping arm 32.This is followed by seaming and cutting off of the plastic, film 22, asshown in greater detail in FIG. 11.

FIG. 11 shows a detail of FIG. 10. It can be seen in the figure that atleast one plastic film 22 layer has come under pressure on two sides ofthe gripping arm 32. In the figure, above the gripping arm 32, the firstseaming layer 27 and the second seaming layer 28 are pressed againsteach other tightly between the seaming counterpiece 33 and the grippingarm 32. In addition, in FIG. 11, to the right of the gripping arm 32,the plastic film 22 going away from the package towards the film roll,is pressed between the gripping arm 32 and the gripping counterpiece 31.

FIG. 11 also shows that a heat radiator 34, preferably an infraredradiator, is placed inside the gripping arm 32. FIG. 11 further showsthat a seaming aperture 35 is formed in the gripping arm 32 wall on theside of the seaming counterpiece 33, and a Cutting aperture 36 is formedin the gripping arm 32 wall on the side of the gripping counterpiece 31.These apertures 35 and 36 are elongated grooves which are locatedtransversely with respect to both the plastic film layers 27 and 28 tobe seamed and the plastic film web 22 to be cut. The purpose of theapertures 35 and 36 is to allow the passage of heat radiation towardsboth the seaming counterpiece 33 and the gripping counterpiece 31. Ofthese apertures, at least the cutting aperture 36 should preferably belong enough to extend right across the plastic film web 22, thusensuring the cutting off of the web.

Seaming and cutting are started by switching on the infrared radiator34, which acts as the heat radiator. The heat radiator then radiatesheat which is able to pass through the apertures made on two sides ofthe gripping arm 32 towards both the seaming counterpiece 33 and thegripping counterpiece 31.

It is known that the electromagnetic rays of the infrared radiator 34will heat any material coming in the way of the radiation the moreefficiently, the better the radiation is absorbed by the material inquestion. The absorbency of the usually transparent PE plastic film usedas packaging material depends, among other things, on the quality,thickness and pretensioning of the plastic film. In general it may,however, be said that plastic film does not absorb heat rays very well.Consequently, the infrared radiator cannot as such be used veryeffectively for heating plastic film. The device would be slow andinefficient.

In the packaging machine relating to the invention, the seaming andcutting of the film has been made efficient by heating at least onecounterpiece on the opposite side of the plastic film web by means ofthe infrared heat radiator. The heating of the plastic film thus takesplace mainly by using indirectly conducted heat. When the infrared heatradiator is in operation, the one or more plastic film layers betweenthe radiator and the counterpiece heat up correspondingly. In order toadjust the temperatures required for seaming and/or cutting to asuitable level, different types of surface materials, different coloursand various shades of darkness, among other things, can be used in thecounterpieces. These alternatives determine the wavelength of theradiation that is absorbed by the plastic film and/or counterpiece.

According to the invention, the surface material used for the seamingcounterpiece 33is, for example, acidified PTFE plastic. By means ofacidification the normally white surface of this plastic is made darker,for example grey or brown. The surface will then absorb the heat raysfrom the infrared radiator 34 to such an extent that it can be heated tothe temperature required for seaming, approximately 100° C., in aboutone second. This thermal energy passes almost immediately to the plasticfilm layers 27 and 28 to be seamed, which are between the seamingcounterpiece 33 and the gripping arm 32, and are then melted, at leastpartly, and welded together. In this example, there are only two plasticfilm layers to be seamed, but there may equally well be more, dependingon the properties of the package desired.

Similarly, the surface material of the cutting counterpiece 31 isselected such that it heats up as efficiently as possible. A moresignificant property than the choice of material of the cuttingcounterpiece 31 is, however, its colour. Therefore, according to oneadvantageous embodiment, the said surface is painted black, which meansthat it will absorb radiation almost completely. The infrared radiationabsorbed by the black surface of the cutting counterpiece 31 does infact heat the surface up to several hundred degrees within about onesecond. As a result, this thermal energy is conducted to the plasticfilm 22 between the cutting counterpiece 31 and the gripping arm 32,which immediately melts the film and cuts it off.

Since the infrared heat radiator 34 inside the gripping arm 32 heats upsimultaneously both the seaming counterpiece 33, through the aperture35, and the gripping counterpiece, 31, through the aperture 36, theseaming of the seaming film layers 27 and 28 and the cutting of theplastic film web 22 take place almost simultaneously. This manner ofoperation makes the packaging device relating to the inventionsubstantially more efficient and simpler than known devices. This alsohas considerable significance for the operating speed of the packagingdevice.

Subsequent to the seaming of the seaming film layers 27 and 28 and thecutting of the plastic film web 22 going to the film roll, the operationof the packaging machine continues automatically so that the seamingcounterpiece 33 or the separate seaming surface belonging to it is movedaway from the gripping arm 32. The seaming films 27 and 28 will then bereleased from the pressure exerted on it by the gripping counterpiece 32and the seaming counterpiece 33, thus detaching the entire gripping unitfrom the object to be packaged. The seaming counterpiece 33 is now readyto be lifted away from between the film layers.

The lifting of the seaming counterpiece 33 is carried out by lifting theentire gripping unit 30 upwards, as shown in FIG. 12. The packaging ofthe object 20 is then finally completed so that it is wrapped in thedesired manner in the plastic film 22 taken from the film roll 23. FIG.12 shows highlighted the topmost plastic film layers, that is, the firstseaming layer 27 and the second seaming layer 28. Between them is shownthe seam 29 which finishes off the packaging.

Once the object 20 has been packaged, the gripping arm 32, grippingcounterpiece 31 and seaming counterpiece 33 of the gripping unit 30 areturned upwards, to their starting position shown in FIG. 1. The cut,free end 24 of the plastic film web 22 unwinding from the film roll 23is still pressed between the gripping arm 32 and gripping counterpiece31. This enables the packaging of the next object by wrapping to bestarted automatically, as described above.

FIG. 13 shows another embodiment of the plastic film wrapping machine,in which the infrared heat radiator 34 inside the gripping arm 32 hastwo parts. The rear surface of the infrared heat radiator 34 has, forexample, a gilt reflector 40, which means that the heat radiation iseffectively directed towards the apertures 35 and 36 of the gripping arm32. In the wall of the gripping arm 32 two overlapping rows of apertures35 a and 35 b are formed. This ensures that the plastic film webs 27 and28 between the gripping arm 32 and the seaming counterpiece 33 areseamed together at apertures 35 a and 35 b, but cannot be cut off atthis point. The apertures 35 a and 35 b in the wall of the gripping arm32 are shown in greater detail in FIG. 15.

Opposite the apertures 35 a and 35 b, the seaming counterpiece 33located against the gripping arm 32 is also formed of two parts. Amoving counterpiece 33 b, made of, for example, brown bakelite, isconnected to the frame part 33a of the seaming counterpiece 33. In theembodiment shown in FIG. 13, a cutting claw 41 is also connected to thegripping counterpiece 31, the point of which claw penetrates into thecutting aperture 36 of the gripping arm 32 at the cutting stage. Thisensures that the cuffing surface of the cutting claw 41 comessufficiently close to the infrared heat radiator 34 and heats up to asufficient temperature. The structure of this detail is shown moreclosely in FIG. 14.

FIG. 14 shows the operation of the cutting claw 41 of the grippingcounterpiece 31. A cutting claw 41 made, for example, of matt blackcarbon alloyed TEFLON™ heats up to such an extent through the radiationfrom the infrared heat radiator 34 that the plastic film web 22 windingaround the point of the cutting claw 41 is cut off almost immediately.Heating is further intensified by shiny plates 42 a and 42 b made, forexample, of stainless steel and positioned on either side of the cuttingclaw 41.

FIG. 15 shows the gripping arm 32 of the plastic film wrapping machineof FIG. 13, as seen from the side. It can be seen in the figure that theaperture rows 35 a and 36 b are positioned so as to overlap. Thisarrangement is a precaution to prevent the plastic film webs situatedagainst the gripping arm 32 from being cut by possible overheating. Thisis due to the necks 43 in the rows of apertures at which points theplastic film webs do not heat up in the same way as at the apertures 35a and 35 b.

It is obvious to a person skilled in the art that the differentembodiments of the invention may vary within the scope of the claimspresented below. The invention is also not limited to the embodimentsdisclosed herein. An alternative solution may be, for example, that boththe seaming counterpiece and the cutting counterpiece have separate heatradiators.

What is claimed is:
 1. A method for treating a plastic film used to wrapan object in a wrapping machine, comprising: wrapping a plastic film webaround the object at least one time to form an overlapping portion ofthe plastic film web and a non-overlapped end portion of the plasticfilm web; placing a seaming heat-absorbent counterpiece under saidoverlapping portion of the plastic film web; pressing said seamingheat-absorbent counterpiece against said overlapping portion of theplastic film web; heating said seaming heat-absorbent counterpiecethrough said overlapping portion of the plastic film web by means of aheat radiating means; and absorbing heat with said seamingheat-absorbent counterpiece from the heat radiating means to heat andseam said overlapping portion of the plastic film web.
 2. The method fortreating a plastic film as claimed in claim 1, wherein said plastic filmweb is wrapped around the object two or more times.
 3. The method fortreating a plastic film as claimed in claim 1, wherein said seamingheat-absorbent counterpiece has a color and degree of darkness arrangedto absorb heat to a temperature required to heat and bond layers of theplastic film web at said overlapping portion of the plastic film web. 4.The method for treating a plastic film as claimed in claim 1, whereinsaid heat radiating means is an infrared heat radiator.
 5. A device fortreating a plastic film used to wrap an object in a plastic filmwrapping machine, comprising: wrapping means for wrapping a plastic filmweb around the object and forming an overlapping portion of the plasticfilm web and a non-overlapped end portion of the plastic film web; aseaming heat-absorbent counterpiece to be placed under said overlappingportion of the plastic film web; means for pressing the seamingheat-absorbent counterpiece against said overlapping portion of theplastic film web; a heat radiating means for heating said seamingheat-absorbent counterpiece through said overlapping portion of theplastic film web; and means for placing said at least one heat radiatingmeans and said seaming heat-absorbent counterpiece on opposite sides ofsaid overlapping portion of the plastic film web.
 6. The device fortreating a plastic film used to wrap an object in a plastic filmwrapping machine of claim 5, wherein said heat radiating means is aninfrared heat radiator.
 7. The device for treating a plastic film usedto wrap an object in a plastic film wrapping machine of claim 6, whereinsaid infrared heat radiator is situated inside said means for pressingthe seaming heat-absorbent counterpiece against said overlapping portionof the plastic film web, and said means for pressing the seamingheat-absorbent counterpiece against said overlapping portion of theplastic film web comprises a tubular means having slots or aperturesthrough which heat radiation is able to pass to the seamingheat-absorbent counterpiece.
 8. The device for treating a plastic filmused to wrap an object in a plastic film wrapping machine of claim 7,wherein said tubular means comprises at least two rows of overlappingseaming apertures.
 9. The device for treating a plastic film used towrap an object in a plastic film wrapping machine of claim 5, whereinsaid seaming heat-absorbent counterpiece has a color and degree ofdarkness arranged to absorb heat to a temperature required to heat andbond layers of the plastic film web at said overlapping portion of theplastic film web.
 10. The device for treating a plastic film used towrap an object in a plastic film wrapping machine of claim 5, whereinsaid seaming heat-absorbent counterpiece is made of brown bakelite. 11.A method for treating a plastic film used to wrap an object in awrapping machine, comprising: wrapping a plastic film web around theobject at least one time to form an overlapping portion of the plasticfilm web and a non-overlapped end portion of the plastic film web;placing a seaming heat-absorbent counterpiece under said overlappingportion of the plastic film web and placing a cutting heat-absorbentcounterpiece under said non-overlapped end portion of the plastic filmweb; pressing said seaming heat-absorbent counterpiece against saidoverlapping portion of the plastic film web and pressing said cuttingheat-absorbent counterpiece against said non-overlapped end portion ofthe plastic film web; heating said seaming heat-absorbent counterpiecethrough said overlapping portion of the plastic film web and heatingsaid cutting heat-absorbent counterpiece through said non-overlapped endportion of the plastic film web by means of at least one heat radiatingmeans; and absorbing heat with said seaming heat-absorbent counterpiecefrom the at least one heat radiating means to heat and seam saidoverlapping portion of the plastic film web and absorbing heat with saidcutting heat-absorbent counterpiece from the at least one heat radiatingmeans to heat and cut said non-overlapped end portion of the plasticfilm web.
 12. The method for treating a plastic film as claimed in claim11, wherein said plastic film web is wrapped around the object two ormore times.
 13. The method for treating a plastic film as claimed inclaim 11, wherein said seaming heat-absorbent counterpiece has a colorand degree of darkness arranged to absorb from to a temperature requiredto heat and bond layers of the plastic film web at said overlappingportion of the plastic film web.
 14. The method for treating a plasticfilm as claimed in claim 11, wherein said at least one heat radiatingmeans is an infrared heat radiator.
 15. The method for treating aplastic film as claimed in claim 11, wherein said at least one heatradiating means is a single infrared heat radiator and is used to heatsaid seaming heat-absorbent counterpiece through said overlappingportion of the plastic film web and to seam said overlapping portion andto heat said cutting heat-absorbent counterpiece through saidnon-overlapped end portion of the plastic film web and to cut saidnon-overlapped end portion.
 16. The method for treating a plastic filmas claimed in claim 11, wherein said at least one heat radiating meanscomprises a first heat radiator used to heat said seaming heat-absorbentcounterpiece through said overlapping portion of the plastic film weband to seam said overlapping portion and a second heat radiator used toheat said cutting heat-absorbent counterpiece through saidnon-overlapped end portion of the plastic film web and to cut saidnon-overlapped end portion.
 17. The method for treating a plastic filmas claimed in claim 11, wherein said cutting heat-absorbent counterpiecehas a color and degree of darkness arranged to absorb heat to atemperature required to heat and cut the plastic film web at saidnon-overlapped portion of the plastic film web.
 18. A device fortreating a plastic film used to wrap an object in a plastic filmwrapping machine, comprising: wrapping means for wrapping a plastic filmweb around the object and forming an overlapping portion of the plasticfilm web and a non-overlapped end portion of the plastic film web; aseaming heat-absorbent counterpiece to be placed under said overlappingportion of the plastic film web and a cutting heat-absorbentcounterpiece to be placed under said non-overlapped end portion of theplastic film web; means for pressing the seaming heat-absorbentcounterpiece against said overlapping portion of the plastic film weband means for pressing the cutting heat-absorbent counterpiece againstsaid non-overlapped end portion of the plastic film web; at least oneheat radiating means for heating said seaming heat-absorbentcounterpiece through said overlapping portion of the plastic film weband said cutting heat-absorbent counterpiece through said non-overlappedend portion of the plastic film web; and means for placing said at leastone heat radiating means and said seaming heat-absorbent counterpiece onopposite sides of said overlapping portion of the plastic film web andfor placing said at least one heat radiating means and said cuttingheat-absorbent counterpiece on opposite sides of the non-overlapped endportion of the plastic film web.
 19. The device for treating a plasticfilm used to wrap an object in a plastic film wrapping machine of claim18, wherein said at least one heat radiating means is an infrared heatradiator.
 20. The device for treating a plastic film used to wrap anobject in a plastic film wrapping machine of claim 18, wherein saidseaming heat-absorbent counterpiece has a color and degree of darknessarranged to absorb heat to a temperature required to heat and bondlayers of the plastic film web at said overlapping portion of theplastic film web.
 21. The device for treating a plastic film used towrap an object in a plastic film wrapping machine of claim 18, whereinsaid cutting heat-absorbent counterpiece has a color and degree ofdarkness arranged to absorb heat to a temperature required to heat andcut the plastic film web at said non-overlapped portion of the plasticfilm web.
 22. The device for treating a plastic film used to wrap anobject in a plastic film wrapping machine of claim 18, wherein said atleast one heat radiating means is one infrared heat radiator for heatingboth said seaming heat-absorbent counterpiece and said cuttingheat-absorbent counterpiece.
 23. The device for treating a plastic filmused to wrap an object in a plastic film wrapping machine of claim 22,wherein said infrared heat radiator is situated inside said means forpressing the seaming heat-absorbent counterpiece against saidoverlapping portion of the plastic film web and the cuttingheat-absorbent counterpiece against said non-overlapped end portion ofthe plastic film web, and said means for pressing the seamingheat-absorbent counterpiece against said overlapping portion of theplastic film web and the means for pressing the cutting heat-absorbentcounterpiece against said non-overlapped end portion of the plastic filmweb comprise a tubular means having slots or apertures through whichheat radiation is able to pass to both the seaming heat-absorbentcounterpiece and the cutting heat-absorbent counterpiece.
 24. The devicefor treating a plastic film used to wrap an object in a plastic filmwrapping machine of claim 23, wherein said cutting heat-absorbentcounterpiece comprises a cutting claw having a point for penetratinginto an aperture of said tubular means so that a cutting surface of thecutting claw is in close proximity to the infrared heat radiator. 25.The device for treating a plastic film used to wrap an object in aplastic film wrapping machine of claim 24, wherein said cutting claw ismade of carbon alloyed material.
 26. The device for treating a plasticfilm used to wrap an object in a plastic film wrapping machine of claim24, wherein reflective plates are provided on either side of saidcutting claw.
 27. The device for treating a plastic film used to wrap anobject in a plastic film wrapping machine of claim 23, wherein saidtubular means comprises a cutting aperture and at least two rows ofoverlapping seaming apertures.
 28. The device for treating a plasticfilm used to wrap an object in a plastic film wrapping machine of claim18, wherein said at least one heat radiating means comprises twoinfrared heat radiators and reflecting means.
 29. The device fortreating a plastic film used to wrap an object in a plastic filmwrapping machine of claim 18, wherein said seaming heat-absorbentcounterpiece is made of brown bakelite.
 30. A method for treating aplastic film used to wrap an object in a wrapping machine, comprising;wrapping a plastic film web around the object at least one time to forman overlapping portion of the plastic film web and a non-overlapped endportion of the plastic film web; placing a cutting heat-absorbentcounterpiece under said non-overlapped end portion of the plastic filmweb; pressing said cutting heat-absorbent counterpiece against saidnon-overlapped end portion of the plastic film web heating said cuttingheat-absorbent counterpiece through said non-overlapped end portion ofthe plastic film web by means of a heat radiating means; and absorbingheat with said cutting heat-absorbent counterpiece from the heatradiating means to heat and cut said non-overlapped end portion of theplastic film web.
 31. The method for treating a plastic film as claimedin claim 30, wherein said plastic film web is wrapped around the objecttwo or more times.
 32. The method for treating a plastic film as claimedin claim 30, wherein said heat radiating means is an infrared heatradiator.
 33. The method for treating a plastic film as claimed in claim30, wherein said cutting heat-absorbent counterpiece has a color anddegree of darkness arranged to absorb heat to a temperature required toheat and cut the plastic film web at said non-overlapped portion of theplastic film web.
 34. A device for treating a plastic film used to wrapan object in a plastic film wrapping machine, comprising: wrapping meansfor wrapping a plastic film web around the object and forming anoverlapping portion of the plastic film web and a non-overlapped endportion of the plastic film web; a cutting heat-absorbent counterpieceto be placed under said non-overlapped end portion of the plastic filmweb; means for pressing the cutting heat-absorbent counterpiece againstsaid non-overlapped end portion of the plastic film web; heat radiatingmeans for heating said cutting heat-absorbent counterpiece through saidnon-overlapped end portion of the plastic film web; and means forplacing said heat radiating means and said cutting heat-absorbentcounterpiece on opposite sides of the non-overlapped end portion of theplastic film web.
 35. The device for treating a plastic film used towrap an object in a plastic film wrapping machine of claim 34, whereinsaid heat radiating means is an infrared heat radiator.
 36. The devicefor treating a plastic film used to wrap an object in a plastic filmwrapping machine of claim 34, wherein said cutting heat-absorbentcounterpiece has a color and degree of darkness arranged to absorb heatto a temperature required to heat and cut the plastic film web at saidnon-overlapped portion of the plastic film web.
 37. The device fortreating a plastic film used to wrap an object in a plastic filmwrapping machine of claim 34, wherein said infrared heat radiator issituated inside said means for pressing the cutting heat-absorbentcounterpiece against said non-overlapped end portion of the plastic filmweb, and said means for pressing the cutting heat-absorbent counterpieceagainst said non-overlapped end portion of the plastic film webcomprises a tubular means having one or more slots or apertures throughwhich heat radiation is able to pass to the cutting heat-absorbentcounterpiece.
 38. The device for treating a plastic film used to wrap anobject in a plastic film wrapping machine of claim 37, wherein saidcutting heat-absorbent counterpiece comprises a cutting claw having apoint which is capable of penetrating into an aperture of said tubularmeans so that a cutting surface of the cutting claw is in closeproximity to the infrared heat radiator.
 39. The device for treating aplastic film used to wrap an object in a plastic film wrapping machineof claim 37, wherein said tubular means comprises a cutting aperture.40. The device for treating a plastic film used to wrap an object in aplastic film wrapping machine of claim 37, wherein said cutting claw ismade of carbon alloyed material.
 41. The device for treating a plasticfilm used to wrap an object in a plastic film wrapping machine of claim37, wherein reflective plates are provided on either side of saidcutting claw.